1. Field of the Invention
The present invention relates to a hot water type heat exchange apparatus, such as a heater core or radiator, able to be connected to a water pump driven by an internal combustion engine.
2. Description of the Related Art
Japanese Utility Model Publication 55-163209 discloses a switchable heater core having a first cooling water circuit for obtaining a U-shaped flow of hot water, a second cooling water circuit for obtaining a one directional flow of hot water, and a thermo-sensitive valve for switching between the first and the second circuits in response to the temperature of the hot water.
In this prior art heater core, the amount of hot water supplied to the heater core is determined from a point at which the hot water supply performance by a water pump driven by an internal combustion engine and the flow resistance through the heater core are balanced. Namely, under a low engine rotational speed condition, such as an idling condition of the engine, the amount of hot water supplied to the heater core is reduced, and this causes the amount of heat emitted at the heater core to be reduced.